Selective naphtha hydrocracking

ABSTRACT

1. A PROCESS COMPRISING CONTACTING A GASOLINE BOILING RANGE VIRGIN NAPHTHA WITH A CATALYST CONSISTING ESSENTIALLY OF ZSM-5 TYPE OF ALUMINO-SILICA ZEOLITE HAVING A HYDROGENATION/DEHYDROGENATION COMPONENT THEREIN IN ADMIXTURE WITH ADDED HYDROGEN IN A HYDROGEN TO HYDROCARBON RATIO OF ABOUT 1 TO 10, AT ABOUT 600 TO 800*F., 50 TO 1000 P.S.I.G. AND 0.5 TO 10 WHSV, UNDER SUCH COMBINATION OF CONDITIONS AS TO HYDROCRACK AT LEAST ABOUT 40 WT. PERCENT OF SAID VIRGIN NAPHTHA TO PENTANE AND LIGHTER PRODUCTS HAVING A C3 TO C4 RATIO OF ABOUT 1.0 TO 1.4, AND AN N-C4 TO I-C4 RATIO OF ABOUT 0.85-1.2; WHICH PROCESS ALSO PRODUCES UP TO ABOUT 60 WT. PERCENT OF A C6+ LIQUID PRODUCT HAVING A MINIMUM CLEAR RESEARCH OCTANE NUMBER OF ABOUT 80, WHICH LIQUID PRODUCT HAS AN OCTANE NUMBER OF AT LEAST ABOUT 40 UNITS HIGHER THAN SAID FEED.

nt. 22, 1974 RQA, MORRlsQN ETAL SELECTIVE NAPHTHA HYDROCRACKING aunaual-ch 2s. 1973 i s 'sheets-sheet 1 A g +I) Sele-activ H ydrocrackmgPlant Oct. 22, 1974 R, A, MORRlSON ETAL 3,843,510

SELECTIVE NAPHTHA HYDROCRACKING I5 Sheets-Sheet 5 Filed Ilarch 23, 1973m\\ w38 E03 United States Patent 3,843,510 SELECTIVE NAPHTHAHYDROCRACKING Roger A. Morrison, West Deptford, NJ., and John J. Wise,Media, Pa., assignors to Mobil Oil Corporation Filed Mar. 23, 1973, Ser.No. 344,453 Int. Cl. Cg 13/10 U.S. Cl. 208-111 10 Claims ABSTRACT OF THEDISCLOSURE A process for converting virgin straight run naphtha to a gaswhich is predominantly saturated C3-C5 and a C6+ liquid which has asubstantially higher octane number than the feed. The process includescontacting the virgin straight run naphtha together with added hydrogenwith a catalyst of the ZSM-S type aluminosilicate zeolite containing ahydrogenation/dehydrogenation component at relatively mild temperaturesand space velocities, and pressure high enough to induce hydrocracking.The gas product can be used as such as I PG (liquified petroleum gas) oras feed to a pyrolysis unit for cracking to olefins, particularlyethylene, propylene and some higher homologues.

This invention relates to hydrocarbon conversion. It more particularlyrefers to conversion of naphtha into mode desirable products.

It is known to crack virgin straight run naphtha C6 to 330 F. stock,under conditions such as to produce a gas product, in which ethylene andpropylene predominate, and a liquid product boiling in the gasolinerange known as pyrolysis gasoline. This pyrolysis gasoline is rich inaromatics and as such is conveniently blendable into a refinery gasolinepool.

Recently, government actions in various parts of the world havenecessitated a reduction in the benzene content of gasoline sold in suchlocalities and therefore, indirectly these actions have limited theamount of pyrolysis gasoline which can be blended directly into thegasoline pool without prior removal of at least some of the benzenetherefrom. This limit on the tolerable benzene limits in turn forces thepetroleum refiner to produce less pyrolysis gasoline, which means aconcommitant reduction in light oleiins production, or it requires thereliner to further treat produced pyrolysis gasoline, e.g. bydistillation, to remove all or part of the benzene content thereof.Neither of these solutions are satisfactory from an economics point ofview because on the one hand the pyrolysis unit is operating atsubstantially less than capacity and therefore inefficiently, and on theother hand sepbenzene must be cleaned up and disposed of for chemicalsuse, if possible, or burned in the refinery for its heat value.

Liquified petroleum gas (LPG) is a commodity petroleum product. It isused principally in the home and remote (camping and trailering)locations for providing heat for comfort and for cooking. Although thedemand for LPG is not presently so great in the United .States that thisdemand cannot be satisfied from available petroleum fractions, it isanticipated that this demand will continually rise in the near future.In some parts of the world, there is a substantially larger proportionaldemand for LPG. In some cases this demand exceeds the quantity of LPGwhich can reasonably be recovered from petroleum without chemicalprocessing (e.g. cracking or reforming). LPG is principally propanewhich may have Patented Oct. 22, 1974 more or less ethane, propyleneand/or butane admixed therewith.

One specification for commercial LPG is:

Tests 1 Limits Vapor pressure at 100 F., p.s.i.g., Max. 200. BoilingPt., F., Max 37. Volatile Sulfur, gr./ C F., Max.2 15.

Corrosion, l Hr. at 100 F., ASTM Strip Max. 1. Dryness, Cobalt BromideTest3 Pass. HZS, Lead Acetate Test4 Do. Residue Test Do. Oil Ring TestDo. Odorization, lbs. Ethyl Mercaptan/ 10,000 gal. 1.5. Composition:

Propane and/ or Propylene, percent, Min. 95. Ethane, percent, Max 3.

1 Test methods are given in NGPA publication 2140.

2 Test shall be run before odorizing the product.

.If Dew Point Test is used, Dew Point lower than 15 mdleates moisturefree product.

4Proposed ASTM method for detection of HQS in LPG.

It is known to use various zeolite catalysts to accomplish varioushydrocarbon conversions. Small pore (less than about 5 Angstrom Units)zeolites are considered to be shape selective catalysts because theywill act on straight chain (normal) parafiins while passing isoparaffinssubstantially unaltered. Large pore (over about l1 Angstrom units)zeolites are not shape selective in that they will admit andcatalytically act upon substantially all of the hydrocarbons in usualpetroleum feedstocks regardless of configuration.

More recently there has been developed an intermediate type of zeoliticmaterial which seems to have an eliptical pore opening of such size andshape as to be able to admit not only normal parains, but slightlybranched materials as well. This newer type of material is known as aZSM-S type of synthetic aluminosilicate zeolite.

ZSM-S aluminosilicate zeolitic material is a family of catalyticmaterials which includes not only ZSM-S itself but also ZSM-8, ZSM-11,and other similarly behaving zeolites.

`ZSM-S is disclosed and claimed in copending application Ser. No.865,472, filed Oct. 10, 1969; ZSM-S is disclosed and claimed incopending application Ser. No. 865,418, filed Oct. 10, 1969, and ZSM-11is disclosed and claimed in copending application Ser. No. 31,421 filedApr. 23, 1970.

The family of ZSM-S compositions has the characteristic X-raydiffraction pattern set forth in Table 1 hereinbelow. ZSM-5 compositionscan also be identified, in terms of mole ratios of oxides, as follows:

gallium, Y is selected from the group consisting of silicon andgermanium, z is from 0 toi-40 and b is at least 5 and `preferably15-300. I n a preferred synthesized form, the

zeolite hasv a formula, in terms of mole ratios of oxides, as follows:

- 0.9 :l: 0.2M2 0: A1203: 15-100SiO2I2Hz0 and M is selected from thegroup consisting of a mixture of alkali metal cations, especially sodiumand alkyl ammonium ions, especially tetraalkylammonium cations, thealkyl groups of which preferably contain 2-5 carbon atoms. l

In a preferred embodiment of ZSM-S, W is aluminum, Y is silicon and thesilica/alumina mole ratio is at least 15, preferably at least 30. v

Members of the family of ZSM-S zeolites which include ZSM-S, ZSM-8 andZSM-ll possess a definite distinguishing crystalline structure WhoseX-ray diffraction pattern shows the following significant lines:

These values, as well as all other X-ray data were determined bystandard techniques. The radiation was the K- alpha doublet of copper,and a scintillation counter spectrometer with a strip chart pen recorderwas used. The peak heights, I, and the positions as a function of 2times theta, where theta is the Bragg angle, were read from thespectrometer chart. From these the relative intensities, 100 I/Io whereI0 is the intensity of the strongest line or peak, and d(obs.), theinterplanar spacing in A, corresponding to the recorded lines, werecalculated. In Table 3 the relative intensities are given in terms ofthe symbols S=strong, M=medium, MS=medium strong, MW=me dium weak andVS=very strong. It should be understood that this X-ray dilractionpattern is characteristic of all the species of ZSM-S compositions. Ionexchange of the v a composition, in terms of mole ratios of oxides,falling within the following rangestj TABLE 2 Parueularly f BroadPreferred preferred oH-/Si02 nor-1.0 0.1-0.8 i12-(L75 RrN-t/(RiNH-Naf)0.2-0.95 0.3-0.9 v0.4-0.9 Hgo/olaz 10-300 10-300 10-300 Yor/Wzoa 5-100,A-1osc tti-4o wherein R is propyl, W is aluminum and Y is silicon. Thismixture is maintained at reaction conditions. untilI the crystals of thezeolite are formed. Thereafter the` crystals are separated from theliquid and recovered. Typical reaction conditions consist of atemperature of from about C. to 175 C. for a period of about six hoursto 60 days. A more preferred temperature range is from about 4 to 15 0"C., with the amount of time at a temperature in such range being fromabout 12 hours to 20 days.

The digestion of the gel particles is carried out until crystals form.The solid product is separated from the reaction medium, as by coolingthe whole to room temperature, filtering and water Washing.

ZSM-S is preferably formed as an aluminosilicate. The composition can beprepared utilizing materials which supply the elements of theappropriate oxide. Such compositions include, for an aluminosilicate,sodium aluminate, alumina, sodium silicate, silica hydrosol, silica gel,silicio acid, sodium hydroxide and tetrapropylammonium hydroxide. Itwill be understood that each oxide component utilized in the reactionmixture for preparing a member of the ZSM-S family can be supplied byone or more initial reactants and they can be mixed together in anyorder. lFor example, sodium oxide can be supplied by an aqueous solutionof sodium hydroxide, or by an aqueous solution of sodium silicate;tetrapropylammonium cation can be supplied by the bromide salt. Thereaction mixture can be prepared either batchwise or continuously.Crystal size and crystallization time of the ZSM-S composition will varywith the nature of the reaction mixture employed.

ZSM-S can also be identied, in terms of mole ratios of oxides, asfollows:

mlm

wherein M is at least one cation, n is the valence thereof and z is from0 to 40. In a preferred synthesized form, the zeolite has a formula, interms of mole ratios of oxides, as follows:

Ello

and M is selected from the group consisting of a mixture of alkali metalcations, especially sodium, and tetraethylammonium cations.

Zeolite ZSM-8 can be suitably prepared by reacting a water solutioncontaining either tetraethylammoniumhydroxide or tetraethylammoniumbromide together with the elements of sodium oxide, aluminum oxide, andan oxide of silica.

The operable relative proportions of the various ingredients have notbeen fully determined and it is to be immediately understood that notany and all proportions of reactants will operate to produce the desiredzeolite. In fact, completely different zeolites can be preparedutilizing the same starting materials depending upon their relativeconcentration and reaction conditions as is set forth in U.S. 3,308,069.In general, however, it has been found that when tetraethylammoniumhydroxideis employed, ZSM-S can be prepared from said hydroxide, sodiumoxide, aluminum oxide, silica and water by reacting said materials insuch proportions that the forming solution has a composition in terms ofmole ratios of oxides falling within the following ranges: I

Thereafter, the crystals are separated from the liquid and recovered.Typical reaction conditions consist of maintaining the foregoingreaction mixture at a temperature of from about C. to 175 C. for aperiod of time of from about six hours to 60 days. A more preferredhydroxidefrom about 80 to temperature range is from about to 175 C. withthe amount of time at a temperature in such range being from about 12hours to 8 days.

ZSM-ll can also be identified, in terms of mole ratios of oxides, asfollows:

wherein M is at least one cation, n is the valence thereof and z is from6 to 12. In a preferred synthesized form, the zeolite has a formula, interms of mole ratios of oxides, as follows:

o. ein. 3M 2 ozAnoamO-aosiozznro and M is selected from the groupconsisting of a mixture of alkali metal cations, especially sodium, andtetrabutylammonium cations.

ZMS-l1 can be suitably prepared =by preparing a solution containing(R4X)2O, sodium oxide, an oxide of aluminum or gallium, an oxide ofsilicon or germanium and water and having a composition, in terms ofmole ratios of oxides, falling within the following ranges:

wherein R4X is a cation of a quaternary compound of an element of Group5A of the Periodic Table, W is aluminum or gallium and Y is silicon orgermanium maintaining the mixture until crystals of the zeolite areformed. Preferably, crystallization is performed under pressure in anautoclave of static bomb reactor. The temperature ranges from 100 C.-200C. generally, but at lower temperatures, e.g. about 100 C.crystallization time is longer. Thereafter the crystals are separatedfrom the liquid and recovered. The new zeolite is preferably formed inan aluminosilicate form.

An embodiment of this catalyst resides in the use of a porous matrixtogether with the ZSM-S type family of zeolite previously described. Thezeolite can be combined, dispersed, or otherwise intimately admixed withthe porous matrix in such proportions that resulting products containfrom 1 to 95% by weight and preferably from 10 to 70% by weight of thezeolite in the final composite.

The term porous matrix includes non-zeolite inorganic compositions withwhich the zeolites can be combined, dispersed or otherwise intimatelyadmixed wherein the matrix may be catalytically active or inactive. Itis to be understood that the porosity of the composition employed as amatrix can be either inherent in the particular material or it can beintroduced by mechanical or chemical means. Representative of matriceswhich can be employed include metals and alloys thereof, sinteredmetals, and sintered glass, asbestos, silicon carbide, aggregates,pumice, rebrick, diatomaceous earths, alumina and inorganic oxides.Inorganic compositions, especially those comprising alumina and those ofa siliceous nature are preferred. Of these matrices inorganic oxidessuch as clay, chemically treated clays, silica, silica alumina, etc. aswell as alumina, are particularly preferred because of their superiorporosity, attrition resistance and stability.

Techniques for incorporating the ZSM-S type family of zeolites into amatrix are conventional in the art and are set forth in U.S. 3,140,253.

1t is to be noted that when a ZSM-S type zeolite is used in combinationwith a porous matrix, space velocities which may be set forth asparameters for a process using such material are based on the ZSM-S typezeolite alone and the porous matrix is ignored. Thus, whether a ZSM-Stype zeolite is used alone or in a porous matrix, the space` velocitiesin al1 cases refer to the ZSM-5 type component` It is known thatzeolites, particularly synthetic zeolites, can have their compositionmodified by impregnating certain metals thereonto and/or thereinto. Thecomposition can also be modified by exchanging various anions and/orcations into the crystal structure of the zeolite, replacing more orless of the ions originally present upon production of the zeolite.

Typical cations replacing the original sodium or part of the sodiuminclude hydrogen, ammonium, and metal cations, including mixtures ofthese. Of the replacing cations, preference is given to hydrogen,ammonium, rare earth, metals, magnesium, zinc, cadium, calcium, nickelrhenium and mixtures thereof.

Typical ion exchange techniques would be to contact a ZSM-S type ofzeolite with a salt of the desired replacing cation or cations. Althougha wide variety of salts can be employed, particular preference is givento chlorides, nitrates and sulfates.

Representative ion exchange techniques are disclosed in a wide varietyof patents, including U.S. 3,140,249; 3,140,- 251; and 3,140,253

As noted above, it is possible to incorporate a desired metalliccomponent onto the ZSM-S type family of zeolites by techniques otherthan ion exchange Thus, for example, it is possible to impregnate adesired metallic component, such as zinc, platinum or palladiumthereinto by conventional impregnation techniques, as well as merelydepositing the elemental metal onto the particular zeolite and in somecases, such as with zinc oxide, to incorporate the metal by physicaladmixture of the zeolite with a substantially insoluble compound of themetal.

In any event, following contact with a salt solution of the desiredreplacing cation, the zeolites are preferably Washed with water anddried at a temperature ranging from to about 600 F. and thereafterheated in air or inert gas at temperatures ranging from about 500 W. to1500" F. for periods of time ranging from 1 to 48 hours or more. It isnoted that this heat treatment can be carried out in situ, i.e. whilethe particular reaction being catalyzed by the ZSM-5 type of zeolite istaking place, but it is preferred to carry it out as a separate stepprior to carrying out the reaction.

ZSM-S type of zeolites have been disclosed to be useful in aromatizingpetroleum fractions, boiling up to about 380 F. which are parainic,olenic and/or naphthenic in nature, by treating these fractions at about650 to 1500 F. under high severity conditions in the absence of addedhydrogen (see Applications Ser. Nos.. 153,885 and 253,942 led June 16,1971 and May 17, 1972 respectively). These zeolites containing ahydrogenation/dehydrogenation component have also been disclosed asuseful catalysts in dewaxing 350 F.| fractions by treating such at about650 F. to 1000 F., 100 to 300 p.s.i.g., a space velocity equivalent toabout 0.1 to 10 LHSV and an added hydrogen to hydrocarbon ratio ofbetween about 1 and 20. In the aromatization process referred to above,a substantial portion of the feed is converted to a C5 gas (pentanes andlighter).

It is an object of this invention to provide a novel process ofconverting virgin straight run naphtha to more desirable products.

It is another object of this invention to provide a process ofconverting virgin straight run naphtha to lower olens and high octanegasoline while minimizing benzene production.

It is a further object of this invention to provide a process ofconverting virgin straight run naphtha to a high octane gasoline blendstock having a low sulfur and a low benzene content.

lA still further object of this invention is to produce a synthetic LPGwhich is compatible with natural LPG.

Other and additional objects of this invention will become apparent froma consideration of this entire specication including the drawing and theclaims hereof.

Understanding of this invention will be facilitated by reference to theaccompanying drawing in which:

iFIG. 1 is a schematic dow sheet showing one process according to thisinvention;

FIG. 2 is similar to FIG. 1 showing a modified process in accord withthis invention; and

FIG. 3 is similar to FIG. 1 showing a modified process in accord withthis invention.

In accord with and fulfilling these objects, one aspect of thisinvention resides in a process comprising contacting a gasoline boilingrange virgin straight run naphtha with a ZSM-S type of syntheticaluminosilicate zeolite catalyst containing ahydrogenation/dehydrogenation component at an elevated temperature ofabout 600 to 800 F., an elevated pressure of about S to 1000 p.s.i.g., aspace velocity of about l0.5 t0 l0 WHSV and an added hydrogen tohydrocarbon ratio of about 1 to 10 under such combination of theseconditions as to hydrocrack said naphtha into a C gaseous fraction and aCsi' liquid fraction at a conversion of at least about 40% in a gas toliquid ratio of about l to 2; with the liquid fraction having a benzenecontent of less than about 5%, and with the gas fraction containing a C3to C4 ratio of about 1.0 to 1.4, an n-C4 to i-'C4 ratio of about 0.85 to1.2.

The liquid product produced according to this process is remarkably goodgasoline blend stock, it having a clear research octane number of atleast about 91. Under some reaction conditions, that is higher severityat a conversion of at least about 75%, it is practical to produce a C5+liquid gasoline product having a still higher clear research octanenumber of at least about 94.

Preferred operating conditions for the virgin naphtha hydrocrackingprocess of this invention are: temperature 625 to 725 F.; pressure 500to 800 p.s.i.g.; space velocity 1 to 5 LHSV; and added hydrogen tohydrocarbon ratio 4 to 6.

The ZSMS type of catalyst used in the instant process must have ahydrogenation/dehydrogenation component therein. This component can beincorporated by impregnation and/ or ion exchange as desired. Theproportion of such component should be about 0.1 to 1.0% by Weight basedupon the weight of the zeolite portion of the catalyst mass. Exemplaryhydrogenation/dehydrogenation components which are useful in thepractice of this invention include metals, oxides and sulides of metalsof the Periodic Table which fall in Group VIB including chromium,molybdenum, tungsten and the like Group IIB including zinc and cadmium.Group VIIB including manganese and rhenium, Group VIII including cobalt,nickel, platinum, palladium, ruthenium, rhodium, rhenium and the like,and combinations of metals, suliides and oxides of metals of Groups VIband VIII such as nickel-tungsten sulfide, cobalt molybdenum oxide andthe like. These hydrogenation/dehydrogenation components are especiallyillustrated by nickel, palladium, platinum, ruthenium, rhenium, cobalt,zine and the like. Under some circumstances a very stronghydrogenation/dehydrogenation component such as nickel is preferredWhereas under other circumstances a milder acting catalyst such as zincmay l be more desirable. This depends to a great extent upon thetemperature and pressure of the hydrocracking processs and the tolerablelimits of aromatic's, as opposed to naphthenes, in the liquid product.Y.

The products produced by this mild hydrocracking of the naphtha feed incontact with ZSM.-5 type of zeolite catalyst are excellent productsWithout further processing. As noted above, the liquid product is verygood gasoline. 'Ihe gas product produced under 'these hydrocrackingconditions is an unusually excellent material for conversion to LPG. Inthis aspect of this invention, this gas is separated into a Cl-CZfraction and a C3-,C5 fraction. The C1-C2 fraction is suitably used orsold for fuel while the C3-C5 fraction is condensed to LPG. In apreferred embodiment of this aspect of this invention it has been foundto be quite suitable to separate an iso-C4 fraction from the (i3-C5 gasfraction and to use this fraction as feed for alkylation.

In another aspect of this invention the gas product produced by thismild hydrocracking is not resolved but is fed in its entirety to -apyrolysis unit which may be operl ated conventionally to maximize theproduction of olens and hydrogen. This pyrolysis has as its main purposeto convert the C5 gas product of hydrocracking to predominantly C2 'andC3 oleiins, perhaps with some olenic C4 content, and produce some liquidpyrolysis gasoline byproduct. One of the most desirable things aboutthis combination of process steps, as opposed to direct pyrolysis ofstraight run naphtha without intermediate hydro-l cracking, is that lesspyrolysis gasoline is produced upon cracking the C5 gas produced byhydrocracking than with straight run naphtha feed for the sameequivalent ethylene production. Blending the hydrocracked gasoline withthe pyrolysis gasoline gives acceptable total yields of gasoline withreasonably high octane numbers without the` adversity of high benzenecontent.

A further aspect of this invention is in using the gasoline produced inthis process, hydrocracked liquid product, pyrolysis gasoline or both,as reformer feed. Mild reforming of this product increases the octanevalue thereof without excessive loss of volume or production of benzene.Further, since the liquids produced by the process of this invention arevery low in sulfur content, they do not need pretreating before beingreformed.

A byproduct of pyrolysis is hydrogen generated in olelins production.This hydrogen can be used as the necessary added hydrogen feed to thehydrocracking unit referred to above. Where necessary or desirable,additional quantities of hyrogen can be fed to the hyrocracking unitfrom other sources or some of the hydrogen produced during pyrolysis canbe separated for other uses in order to provide the correct, desiredhydrogen to hydrocarbon ratio.

Referring now to FIG. l, a virgin straight run naphtha 10, such as C5330F. light Arabian stock, is fed to a hydrocracking converter 12containing a suitable quantity of a ZSM-S type catalyst 14. Hydrogen 16is also fed into the converter 12. There are produced in the converter12 a C54' liquid product 18 gas product which is suitably split into aCl-C2 fraction 19, an iso-C4 fraction 20 which may be fed to alkylation,and the remaining Ca-C., fraction 21 which is used as LPG.

As shown in FIG. 2, the liquid product 18 is gasoline blend stock whilethe unresolved gas product 22 may be fed to a pyrolysis unit 23, whichmay be thermal or catalytic in nature (the unit shown is of thecatalytic 24 variety). There are produced in the pyrolysis unitpyrolysis gasoline liquid product 26, anda mixed gas product 27 which isrich in olefins and hydrogen. The liquid pyrolysis gasoline product 26maybe separately used or it may be blended with the C5+ liquid product18 from the hydrocracking converter 12 to form `a total gasoline rangeproduct 30.

The olens stream 28 evolved from pyrolysis is suitably resolved by4known techniques in a gas plant operation 32 which may includedistillation and/or extraction opera tions. There are produced from thisgas plant 32 a hydrof gen stream 16, part or all of which is recycled tothe hydrocracker 12, a light gas stream 34 which may be rich in methaneand therefore can be used as fuel or perhaps vented,an ethylene stream36 and a higher olefins stream 38 which is predominantly propylenehaving some proportion of butylenes and/or pentylencs admixed there-vwith. This higher olefins stream may be further resolved to producehigh'grade propylene and other oletins as desired. Y

Referring now to FIG. 3, a virgin straight run` naphtha 50 is fed intocontact with a ZSM-S type catalyst 52 together with hydrogen 54 underhydrocrackingconditions in a converter 56. There are produced in theconverter 56,

a C1C2 gas 57 and a C3C4 gas 58 which is fed to a pyrolysis unit 60which in turn produced a liquid pyrolysis gasoline product 62 and a gasproduct `64. The converter 56 also produces a liquid product 66 which isrelatively high octane gasoline. This C5+ liquid 66 is fed to a reformer68 for mild reforming in or-der to increase the octane value even morewithout significantly reducing the volume of the liquid product butstill producing a reformer gas effluent containing mainly hydrogen andCf. This gas can be recovered and used as fuel or fed to the pyrolysisunit 60 as Idesired.

This liquid reformate 70 is suitably blended with pyrolysis gasoline 62to form' a gasoline product 72. It may alternatively be desirable toblend the pyrolysis gasoline 62 with the hydrocracking C5+ liquid 66before reforming 68.

The gas product 64 of pyrolysis is an olens rich material which isresolved in a splitting operation 74 into recycle hydrogen 54, lightgases 76, ethylene 78` and higher oleiins 80.

This invention will be illustrated by references to the followingexamples which are not to be construed as limiting on the scope hereof.In these examples parts and percentages are by weight unless specifiedto the contrary.

EXAMPLE 1 A virgin light Arabian-naphtha charge stock having thefollowing characteristics: Y

Charge, Arabian Naphtha Gravity, API 63.2 Sp. Gr. 60/60 F 0.7268 Sulfur,p.p.m 290 Octane Number, C6+:

R+3 64 R-l-O 40 C6+ PONA Analysis:

Total Parains 63.5 Total Olens Monocycloparains 19.2 Dicycloparans 0.9Cyclooleiins 0 Total Naphthenes 20.1 Alkylbenzenes 16.3 Indanes andTetralins 0.1 Naphthalenes 0 Total Aromatics 16.4 Parain Distribution:

C5 0.1 C6 9.1 Cf, 14.4 C8 15.9 C9 17.8 C10 5.5 Cn 0 C12 0 AromaticDistribution:

C8 0.7 C, 3.3 C8 6.5 C9 5.5 C10 0.4 Combined Hydrogen 14.55 MolecularA`Weight:

7. Parains v y 110.1 Aromatics 105.9 Dicycloparains 1 l 3 .3 C6+ Total109.3

was hydrocracked by contacting such with hydrogen and a ZSM-S catalysthaving a silicon to aluminum ratio of at 650 to 665 F. ata pressure ofabout 650 p.s.i.g. for about two (2) weeks. The space velocity wasAmaintained at about 3 and the hydrogen feed was sulicient to provide ahydrogen toV hydrocarbon ratio of about 5 to 1.

10 The catalyst which was used had been pretreated with hydrogen at 650p.s.i.g. and 900 F. for 1 hour. The hydrogenation/dehydrogenationcomponent was nickel, which was present in a proportion of 0.4%.

The following Table 2 sets forth the properties of the C5- gas product:

Wt. percent of total Percent of C5- product Properties of liquid Cri'Charge Product The following Table 3 sets forth the physical propertiesof the C6+ liquid product:

TABLE 3 Gravity, API 47.4 Sp. Gr. 60/60 F 0.7908 Sulfur, p.p.m. 10Octane Number, C6+z R+3 96 R-l-O 91 C6+ PONA Analysis:

Total Parains 35.0 Total Olens 0.6 Monocycloparans 19.2 Dicycloparains0.5 Cyclooleiins 0 Total Naphthenes 19.7 Alkylbenzenes 41.2 Indanes andTetralins 4.7 Naphthalenes 0.9 Total Aromatics 44.8 Parain Distribution:

C7 3.8 C8 4.6 C9 10.2 C10 4.9 C11 0 C12 0 Aromatic Distribution:

C6 2.1 C7 10.4 Cs 14.9 C9 9.8 C10 2.4 C11 1.1 C12 0.4 CombinedHydrogen'` Molecular Weight:

Paraffins 107.2 Aromatics .4 Dicycloparains 1 13.8 C6+ Total 107.0

The following Table 4 sets forth the compound distri- TABLE 4 [ReactionI Arabian Naphtha (C0 330 F.) over 65% NiHZSM-5 35% A1203] i ion in theC51 liquid product (hours) 1.5 1.5

but

Time Ori-stream 0.1... Wm .om L 0. LL2.0.0. L 80005 Vol percent chargein li ht `uited twas con- K Exam- 111e` 1 and the other was contactedwithstandard com- 65 mercialhydrocracking catalyst.^Tl1e data for theseruns v Conventional 500001.9000050701099722816mm1n10m 0.1 3. .m 1.v 0.0.0.1..00000090009 s. .........0.nu..0-. 00 w .6 .1 0 011000.06.1 01

3907.090000010401099722813MBHJJJ 0.0. 2. .Rm L 0. 0.0.1.0.0.0.0&0.90009.

A chargestock of a Cfr-3 80 F. fract 60 Arabian crude was split intoequal al odws. 2.4. 6. L 0. 0110.00.05. .00.0.0.0 11 o.

Wt..per cent of charge cent of productl 1. 3. 0. l. ik 0. 0

38080240000206.01090722815m9lJJJ 0.0. 2. 3.3. .u L 01.100000 .90000 u 311. .nU ..1

Wt. per- TABLE 6-Cont1nued EXAMPLES Y2 AND 3`Hydrogen/hydroearbdfi-1.121010 ratio I .300602900005070109062281.0@01115.0.0.0.0.0. 01 w nu 1 0 0110000601 1 .TABLE 7.OPERATING CQNDITIONS l..........6..0.a0.0 00 m 5 1 0 0010000 01 l Total.

. .L .0.0. .6. 30.0.09 00 mu 6 1 0 0 10 0 eracked under conditions setforth below designed s to produce the vbest product mix; One -al tactedwith a NZSM-5 catalyst as described (I0-C10 (naphthenes) Cv (aromatics)C10-C11 (Isoparailns) Temperature, F'

V. S H L is set forth in the following Table 7300507300007080W0907218W30611HJ6 0.1L L 3.4 G. .L .1.L0.0.nw .om 90000311. 0 0

.7. 390506300003040W080622830821J7 0.0. 2. 3A 0 L 0.LL00.0. .6. 90009TABLE 5 1. .1.1L .0. .6. 0.0.nm00m 01 MP. 6 1 0 0 00 0 1290004800002060%0896228%2011117 .0.L00.0. .6. 0000.9 00 No. 6 1 O 0 0 132090360000305008952184205M36 .2 00.11.00.000 a 18. 01 .nu .b1 0 1 0. 0.0.00

54m503100002030w07931121804.12%7 0. .L .0. L0.5. 8.00. .6 020% M 7 1 0 00 0 1603060000.1010mu1oo3457F/1QM93WW3 ..............0. 00 n 7 7 5chargel TABLE 6 [Conversions of weight percent product to weight andvolume percent .2.2.6.L .0.4m 0 mw 0 d. 500003351001 1 0 1.

Table 5 shows the selectivities for these wing The follo runs (hours)Selectivit Wt./wt.

CFE

C1IC2- C2"Cs" C3, ISO-C4, X1C4 Ca, ISO-C4, ISO- The following Table 6indicates the conversions and net changes of composition of the chargeas compared to the product:

C1 (lsopar CT (Nephthenes) Examples 2 and 3 were repeated using Nigeriancrude as the source. All operation conditions were the same except forthe operating temperature which was 650 F. The following Table 9 setsforth the composition and properties of charge and product.

TABLE 9 ZSM- Conventional Component Charge treated hydrotreated Weightpercent:

HL -1. 2 -1. 1 0. 2 0. 4 1. 0. 7 22. 7 6. 2 8. 6 12. 2 l0. 4. 8 5. 5 9.3 3. 1 2. 3 49. 7 65. 5 58. 2 77. 1 77 4 94. 1

EXAMPLES 6, 7 AND 8 This series of Examples was run similarly to thoseof Examples 2 and 3 with a C5-360o F. virgin light Arabian naphtha feed.The aliquots contacted with ZSM-S were treated respectively at 596 F.and 642 F. The pressure was 400 p.s.i.g.; the LHSV was 2.5 and thehydrogen to hydrocarbon ratio was 2. The aliquot treated withconventional hydro-treating catalyst was treated at 700 F. at an LHSV of1.2 and the same pressure and hydrogen to hydrocarbon ratio. Thefollowing Table l0 shows the proportion of components of feed andproducts.

TABLE ZSM-5 ZSM- Converb Component Charge (1) (2) tional Weight percent:

The feed to the process of this invention has been stated to be virgingasoline boiling range material. It is intended that such feeddefinition encompass not only fuel range gasoline fraction, i.e. C5 to400 F. naphtha, but also lesser range and partial range material, e.g.C6 to 360 F. or even narrower boiling range material in any portion ofthe full range.

What is claimed is:

1. A process comprising contacting a gasoline boiling range virginnaphtha with a catalyst consisting essentially of ZSM-S type ofalumino-silicate zeolite having a hydrogenation/dehydrogenationcomponent therein in admixture with added hydrogen in a hydrogen tohydrocarbon ratio of about 1 to 10, at about y600 to 800 F., 50 to 1000p.s.i.g. and 0.5 to l0 WHSV, under such combination of conditions as tohydrocrack at least about 40 wt. percent of said virgin naphtha topentane and lighter products having a C3 to C4 ratio of about 1.0 to1.4, and an n-C4 to i-C4 ratio of about 0.85-1.2; which process alsoproduces up to about 60 wt. percent of a C6+ liquid product having aminimum clear research octane number of about 80, which liquid producthas an octane number of at least about 40 units higher than said feed.

2. A process as claimed in claim 1 wherein such combination ofconditions is such as to produce a liquid product having a benzenecontent of less than about 5% by weight.

3. A process as claimed in claim 1 wherein said zeolite is ZSM-S.

4. A process as claimed in claim 1 wherein saidhydrogenation/dehydrogenation component is a member selected from thegroup consisting of nickel, palladium, platinum, ruthenium, rhenium,cobalt, zinc and mixtures thereof.

5. A process as claimed in claim 4 including reforming said C6+ liquidproduct.

6. A process as claimed in claim 1 including pyrolyzing said pentane andlighter gas product to a pyrolysis product comprising predominantlygaseous olens, hydrogen and a gasoline boiling range liquid.

7. A process as claimed in claim 6 including recycling at least aportion of the hydrogen produced in said pyrolysis to saidhydrocracking, and admixing the liquid product from said pyrolysis withthe liquid product of said hydrocracking.

8. A process as claimed in claim 1 including resolving said gas productto a Cl-Cz fraction, an iso-C4 fraction and a remaining C3-C5 fraction.

9. A process as claimed in claim 8 including liquifying said C3-C5fraction.

10. A process as claimed in claim 1 in which LPG is recovered.

References Cited UNITED STATES PATENTS 3,748,251 7/ 1973 Demmel et al.20S-7.4 3,758,403 9/ 1973 Rosinski et al 208-1 ll 3,702,886 11/1972Argauer et al 208-111 3,409,540 ll/1958 Gould et al 208-60 3,497,448 2/1970 Hamner et al 208-60 3,758,628 9/ 1973 Strickland et al 208-603,579,434 5/1971 Smith et al. 208-11 3,729,409 4/ 1973 Chen 208-1353,700,585 10/ 1972 Chen et al 208-111 DELBERT E. GANTZ, Primary ExaminerI. W. HELLWEGE, Assistant Examiner U.S. Cl. X.R.

m30 Umm) STATES PATENT OFFICE CERTIFICATE OF CORRECTION mm no. 3,893,510md october 22, 19711 invented.) ROGER A. MORRISON and JOHN J. WISE It iecertified thet error appeere in the above-identified petent 'end thatseid Lettere Petent ere hereby corrected as sho'wn below:

Column l, line 26 "mode" should be more-- Column l, line 50 "sep" shouldbe "Separated-- Column 11 TABLE L Column Headings Left Right should SideSide Reads Be cl 212.6 l" 0.3" "0.2-- Tsd-chL 1.5 "15.3" 415.2--

C Ill-302" "13,6

Iso-c5 193.9 "6.5" 6.6-- 2,3-DM-cL 193.9 0,9" 0.9--

Sgned and sealed this 14th day of January T975.

(SEAL) Attest:

MecoY 151. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents .J

1. A PROCESS COMPRISING CONTACTING A GASOLINE BOILING RANGE VIRGINNAPHTHA WITH A CATALYST CONSISTING ESSENTIALLY OF ZSM-5 TYPE OFALUMINO-SILICA ZEOLITE HAVING A HYDROGENATION/DEHYDROGENATION COMPONENTTHEREIN IN ADMIXTURE WITH ADDED HYDROGEN IN A HYDROGEN TO HYDROCARBONRATIO OF ABOUT 1 TO 10, AT ABOUT 600 TO 800*F., 50 TO 1000 P.S.I.G. AND0.5 TO 10 WHSV, UNDER SUCH COMBINATION OF CONDITIONS AS TO HYDROCRACK ATLEAST ABOUT 40 WT. PERCENT OF SAID VIRGIN NAPHTHA TO PENTANE AND LIGHTERPRODUCTS HAVING A C3 TO C4 RATIO OF ABOUT 1.0 TO 1.4, AND AN N-C4 TOI-C4 RATIO OF ABOUT 0.85-1.2; WHICH PROCESS ALSO PRODUCES UP TO ABOUT 60WT. PERCENT OF A C6+ LIQUID PRODUCT HAVING A MINIMUM CLEAR RESEARCHOCTANE NUMBER OF ABOUT 80, WHICH LIQUID PRODUCT HAS AN OCTANE NUMBER OFAT LEAST ABOUT 40 UNITS HIGHER THAN SAID FEED.